Computer Graphics
CS 217
Overview • Introduction
What is computer graphics? • Applications
What is it good for? • Systems & software
How does it related to this course?
11 Introduction • What is computer graphics?
Luxo, Jr.
Pixar
What issues must be addressed by a computer graphics system?
22 Overview • Topics in computer graphics
Imaging = representing 2D images
Modeling = representing 3D objects
Rendering = constructing 2D images from 3D models
Animation = simulating changes over time
Overview • Topics in computer graphics
Imaging = representing 2D images
Modeling = representing 3D objects
Rendering = constructing 2D images from 3D models
Animation = simulating changes over time
2D Image
33 What is an Image? • An image is a 2D rectilinear array of pixels
Continuous image Digital image
What is an Image? • An image is a 2D rectilinear array of pixels
Continuous image Digital image AA ppiixxeell iiss aa ssaammppllee,, nnoott aa lliittttllee ssqquuaarree!!
44 What is an Image? • An image is a 2D rectilinear array of pixels
Continuous image Digital image AA ppiixxeell iiss aa ssaammppllee,, nnoott aa lliittttllee ssqquuaarree!!
Representing Digital Images
typedef struct pixel { float red, green, blue; } Pixel;
typedef struct image { int width, height; Pixel *pixels; } Image;
Digital image
55 Image Abstract Data Type
/* Create and delete image */ Image *Image_new(int width, int height); void Image_free(Image *image);
/* Get image properties */ int Image_getWidth(Image *image); int Image_getHeight(Image *image);
/* Pixel manipulation */ Pixel *Image_getPixel(Image *image, int i, int j); void Image_setPixel(Image *image, int i, int j, Pixel *pixel);
/* Image manipulation */ void Image_brighten(Image *image, float factor); void Image_blur(Image *image, float factor); void Image_swirl(Image *image, float angle); void Image_composite(Image *image, Image *image2, Image *mask); void Image_morph(Image *image1, Image *image2, Array *features);
etc.
Processing Digital Images • Examples
Filtering
Warping
Composition
Morphing Image Warping
Image Composition Image Morphing (Michael Bostock, CS426, Fall99) (All students in CS 426, Fall98)
66 Processing Digital Images • Example from the movies …
The Matrix Reloaded (Warner)
Overview • Topics in computer graphics
Imaging = representing 2D images
Modeling = representing 3D objects
Rendering = constructing 2D images from 3D models
Animation = simulating changes over time
3D Model
77 Geometric Modeling
How can this object be represented in a computer?
Example: 3D Polygons
typedef struct point { float x, y, z; } Point;
typedef struct polygon { int npoints; Point *points; } Polygon;
typedef struct object { int npolygons; Polygon *polygons; } Object;
typedef struct scene { int nobjects; Object *objects; } Scene;
88 Example: 3D Polygons
typedef struct point { float x, y, z; (x, y, z) } Point;
typedef struct polygon { int npoints; Point *points; } Polygon;
typedef struct object { int npolygons; Polygon *polygons; } Object;
typedef struct scene { int nobjects; Object *objects; } Scene;
Example: 3D Polygons
typedef struct point { float x, y, z; (x1, y1, z1) } Point; (x2, y2, z2) typedef struct polygon { int npoints; Point *points; } Polygon;
typedef struct object { int npolygons; Polygon *polygons; } Object; (x3, y3, z3) typedef struct scene { int nobjects; Object *objects; } Scene;
99 Example: 3D Polygons
typedef struct point { float x, y, z; } Point;
typedef struct polygon { int npoints; Point *points; } Polygon;
typedef struct object { int npolygons; Polygon *polygons; } Object;
typedef struct scene { int nobjects; Object *objects; } Scene;
Example: 3D Polygons
typedef struct point { float x, y, z; } Point;
typedef struct polygon { int npoints; Point *points; } Polygon;
typedef struct object { int npolygons; Polygon *polygons; } Object;
typedef struct scene { int nobjects; Object *objects; } Scene;
1100 Polygonal Meshes • Can make complex objects
Polygonal Meshes • Can make very complex objects
Stanford Graphics Laboratory
1111 Polygonal Meshes • Can make very complex objects
Stanford Graphics Laboratory
More Geometric Representations
Subdivision Surfaces
Stanford Graphics Laboratory Solids H&B Figure 10.46 Spline Surfaces
1122 Tin Toy
Pixar
Overview • Topics in computer graphics
Imaging = representing 2D images
Modeling = representing 3D objects
Rendering = constructing 2D images from 3D models
Animation = simulating changes over time
1133 Rendering Example
What issues must be addressed by a computer graphics rendering algorithm?
Rendering Methods • Mathematical models for:
Light sources Light
Surface reflectances Source
Camera response • Algorithms to find:
Visible surfaces Surface
Indirect light paths
etc.
Camera
1144 Rendering Methods • Mathematical models for:
Light sources Light
Surface reflectances Source
Camera response • Algorithms to find:
Visible surfaces Surface
Indirect light paths
etc.
Camera
Simple Rendering Algorithm • For each pixel …
Construct ray from eye position through pixel
Find front-most surface intersected by ray
Compute color of sample based on models of light sources and surface reflectances
1155 Simple Rendering Algorithm • For each pixel …
Construct ray from eye position through pixel
Find front-most surface intersected by ray
Compute color of sample based on models of light sources and surface reflectances
Simple Rendering Algorithm • For each pxiel …
Construct ray from eye position through pixel
Find front-most surface intersected by ray
Compute color of sample based on models of light sources and surface reflectances
1166 Simple Rendering Algorithm
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Better Rendering Algorithms • Consider indirect light paths
Inter-object reflections
Caustics
etc.
Trike Rendering Caustics (James Percy, CS 426, Fall99) (Michael Bostock, James Percy & Casey McTaggert, CS 426, Fall99)
1177 Red’s Dream
Pixar
Overview • Topics in computer graphics
Imaging = representing 2D images
Modeling = representing 3D objects
Rendering = constructing 2D images from 3D models
Animation = simulating changes over time
1188 Animation • Describing how models move
Kinematics
Dynamics
Planning
Learning
(Lasseter87)
Animation • Difficult combination of:
Desired behavior
Simulating physics
Artistic control
Hodgins et al.
Chen, Guan, Liu, and Qie CS426, Fall98 Baraff & Witkin
1199 Monsters, Inc.
Pixar
Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization • Training • Education • E-commerce • Computer art
2200 Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization
• Training Jurasic Park (Industrial, Light, & Magic) • Education • E-commerce Geri’s Game • Computer art (Pixar Animation Studios)
Quake (Id Software)
Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization • Training Los Angeles Airport (Bill Jepson, UCLA) • Education • E-commerce
• Computer art Gear Shaft Design (Intergraph Corporation)
Boeing 777 Airplane (Boeing Corporation)
2211 Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization Airflow Inside a Thunderstorm • Training (Bob Wilhelmson, University of Illinois at Urbana-Champaign) • Education • E-commerce • Computer art
Apo A-1 (Theoretical Biophysics Group, Visible Human University of Illinois at Urbana-Champaign) (National Library of Medicine)
Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization Driving Simulation • Training (Evans & Sutherland) • Education • E-commerce
• Computer art Desk Assembly (Silicon Graphics, Inc.)
Flight Simulation (NASA)
2222 Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization • Training • Education • E-commerce • Computer art
Human Skeleton Forum of Trajan (SGI) (Bill Jepson, UCLA)
Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization
• Training Interactive Kitchen Planner (Matsushita) • Education • E-commerce • Computer art
Virtual Phone Store (Lucent Technologies)
2233 Computer Graphics Applications • Entertainment • Computer-aided design • Scientific visualization • Training • Education • E-commerce • Computer art
Blair Arch (Marissa Range & Adam Finkelstein, Princeton University)c
How Is This Related to the Course? • Computer graphics uses …
Parsers (lexical and syntactic analysis)
Abstract data types
Memory management
Multiple processes
Networking
2244 How Is This Related to the Course? • Computer graphics uses …
Parsers (lexical and syntactic analysis)
Abstract data types
Memory management
Multiple processes
Networking
Assembly code (maybe, a little)
Alone in the Dark 4 (Darkworks/Infogrames)
2255